A method and apparatus for controlling lightness in colored inkjet inks by means of a transparent white ink composition

ABSTRACT

A transparent white ink composition is formulated to brighten, lighten and or dilute full-tone primary inkjet colors: cyan; magenta; yellow and black, eliminating the need for ‘light ink’ primary color inks. The transparent white ink is jetted concurrently with reduced amounts of full-tone inks in lighter tonal areas conventionally supported by ‘light ink’ primary inks. Printing ‘light ink’ primary colors using a transparent white ink composition may reduce the number of print channels needed to print all four primary colors and the four ‘light ink’ primary colors. Embodiments of the transparent white ink composition may be solvent- or water-based, drying by evaporation of the carrier fluid. Other embodiments may be radiation-curable ink compositions. An inkjet printer includes print carriage and print head assemblies configured for jetting a primary color ink and the transparent white ink in the same pass in correct proportions to achieve a desired effect.

BACKGROUND

1. Field of the Invention

In general the invention relates to the field of inkjet printing. Moreparticularly, the invention relates to a method and apparatus forcontrolling lightness in colored inkjet inks by means of a transparentwhite ink composition.

2. Background Information

Conventionally, in color inkjet printing, the printer must print severalof the printer's dots for each pixel of an image. Inkjet printers mayprint only a few colors: for example, cyan, magenta, yellow and black.Rendering each pixel of an image into various colors, shades, andintensities requires that the image be dithered, meaning that theprinter creates patterns of dots in multiple colors in order to simulatethe color of each pixel in the image. Additionally, some inkjet printersalso print lighter values of the same four colors. Thus, conventionalinkjet printers now typically use eight colors: cyan, light cyan,magenta, light magenta yellow, light yellow, black and light black.Currently, an inkjet printer's ability to output these eight differentcolors requires an inkjet set that includes at least eight separateinks, with a separate channel devoted to each ink. Thus, modern inkjetprinters must have at least eight print channels. The cost to own andoperate a conventional inkjet printer reflects the manufacturing cost ofproviding a separate channel for each of the colors.

Additionally, large-format or grand-format UV inkjet printers that arecapable of printing with UV-curable white ink are becoming increasinglycommon. The white-ink printing capability, requiring at least oneadditional print channel, adds to the design complexity and themanufacturing cost of such inkjet printers.

Inkjet printing methods wherein inkjet inks are mixed with colorlessliquids just prior to jetting in order to control color density areknown. Additionally, it is known to produce a white inkjet ink havingimproved dispersion stability by mixing a white inkjet ink having apredetermined refractive index with at least one colorless liquid, suchas a dispersant, a photo-initiator or a solvent.

SUMMARY

A transparent white ink composition is formulated to brighten, lightenand or dilute full-tone primary inkjet colors: cyan; magenta; yellow andblack, eliminating the need for ‘light ink’ primary color inks. Thetransparent white ink is jetted concurrently with reduced amounts offull-tone inks in lighter tonal areas conventionally supported by ‘lightink’ primary inks. Printing ‘light ink’ primary colors using atransparent white ink composition may reduce the number of printchannels needed to print all four primary colors and the four ‘lightink’ primary colors. Embodiments of the transparent white inkcomposition may be solvent- or water-based, drying by evaporation of thecarrier fluid. Other embodiments may be radiation-curable inkcompositions. An inkjet printer includes print carriage and print headassemblies configured for jetting a primary color ink and thetransparent white ink in the same pass in correct proportions to achievea desired effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides an illustration of an inkjet printer from a system forcontrolling lightness in colored inkjet inks;

FIG. 2 provides an isometric drawing of a carriage from the printer ofFIG. 1

FIG. 3 provides a schematic diagram of the carriage of FIG. 2

FIG. 4 provides a schematic of the carriage of FIGS. 2 and 3 engaged inthe operation of jetting a composite light primary-color ink onto asubstrate;

FIG. 5 provides a block diagram of a system for controlling lightness incolored inkjet inks by means of a transparent white ink composition; and

FIG. 6 provides a diagram of a machine in the exemplary form of acomputer system within which a set of instructions, for causing themachine to perform any one of the methodologies discussed herein below,may be executed.

DETAILED DESCRIPTION

A transparent white ink composition is formulated to brighten, lightenand or dilute full-tone primary inkjet colors: cyan; magenta; yellow andblack, eliminating the need for ‘light ink’ primary color inks. Thetransparent white ink is jetted concurrently with reduced amounts offull-tone inks in lighter tonal areas conventionally supported by ‘lightink’ primary inks. Printing ‘light ink’ primary colors using atransparent white ink composition may reduce the number of printchannels needed to print all four primary colors and the four ‘lightink’ primary colors. Embodiments of the transparent white inkcomposition may be solvent- or water-based, drying by evaporation of thecarrier fluid. Other embodiments may be radiation-curable inkcompositions. An inkjet printer includes print carriage and print headassemblies configured for jetting a primary color ink and thetransparent white ink in the same pass in correct proportions to achievea desired effect.

In an embodiment, a conventional inkjet printer may be used in thecompositing of transparent white ink with primary color inks to producelight primary color inks. For example, U.S. Pat. No. 7,600,867, theentirety of which is incorporated herein by this reference, describes agrand format hybrid printer with which the principles described hereinmay be implemented. As in the '867 patent, FIG. 1 of the presentapplication shows a printing system 10 adapted for printing images on avariety of substrates. Typical substrates are polyvinyl chloride (PVC)and reinforced vinyl which can be provided with peal-off backings toexpose pressure sensitive adhesive. The printing system 10 is able toprint on flexible as well as on non-flexible substrates, for example,metals, glass, and plastics. The ink deposited on the substrate may bewater or solvent based and may be UV curable. That is, the inks maycontain binders and colorants, as well as photo-initiators andsurfactants. The surfactants are present in the ink to ensure that theink is stable when in the liquid state. The binder generally consists ofa blend of monomers and oligomers, and the photo-initiators are used tocatalyze the polymerization reaction during which the monomers and/oroligomers are joined together to be become a polymeric binder. Thepolymerization generally occurs through a free-radical reaction process.When the energy from a UV source activates the photo-initiator, thephoto-initiator generates free radicals which attack the double bonds inthe monomer or oligomer to initiate polymerization to form a polymerchain. At this point, the binder is now a solid film of polymers thathold the colorant, which consists of pigments and/or dyes, to thesubstrate.

The printing system 10 may include a base 12, a transport belt 14 whichmoves the substrate through the printing system, a rail system 16attached to the base 12, and a carriage 18 coupled to the rail system16. The carriage 18 holds a series of inkjet print heads 20 and one ormore radiation sources, such as UV radiation sources, and may beattached to a belt 22 which wraps around a pair of pulleys (not shown)positioned on either end of the rail system 16. A carriage motor iscoupled to one of the pulleys and rotates the pulley during the printingprocess. As such, when the carriage motor causes the pulley to rotate,the carriage moves linearly back and forth along the rail system 16.

U.S. Pat. No. 7,090,327, the entirety of which is incorporated herein bythis reference, includes one or more carriages, each of which holds aseries of one or more print heads. The series of print heads receivesone or more colored inks from a set of secondary ink containers which isalso mounted to the carriage. In addition, a set of primary inkcontainers supply the inks to the secondary ink containers. In anembodiment, the series of print heads may actually be, for example,eight pairs of print heads, with each pair associated with one of thecolored inks black (K), light black (LK), yellow (Y), light yellow (LY),cyan (C), light cyan (LC), magenta (M), and light magenta (LM). In otherembodiments, the print heads may be associated with any colored ink.Additionally, there can be fewer than or more than 16 print heads. Aprimary ink container and a secondary ink container may supply arespective ink to only one print head or more than two print heads.

U.S. Pat. No. 7,673,965, the entirety of which is incorporated herein bythis reference, describes an inkjet printer that includes one or moreprint head arrays that may be used to produce light primary colors thatare composites of the transparent white ink and full-color primary colorinks. As described in the '965 patent, an inkjet printer may include atleast one print head array containing one or more print heads, each ofwhich includes inkjet nozzles that may be individually controlled toeject a fluid onto a substrate. Fluids may be delivered to the printheads from a fluid reservoir system via conventional tubing systems, viachannels that couple the print heads to the fluid reservoir system, orby other similar systems. Exemplary fluids that may be ejected by inkjetnozzles include colored inks, such as cyan, magenta, yellow or black(“CMYK”) inks, as are commonly used in the printing industry. Coloredinks also may include light cyan, light magenta, light yellow and lightblack

In view of the foregoing, it will be readily understand that a colorchannel includes at least primary and secondary ink containers, or otherink reservoirs, supply lines and print heads for delivering a singlecolor to a substrate. For example, in a carriage that includes a pair ofprint heads for each color, a single color channel may include the pairof print heads for the color, the secondary and primary ink containersfor the color and the tubing and plumbing required to deliver the ink tothe print head and then to the substrate from the ink containers.

Because the use of the transparent white ink to print light primarycolors permits a significant reduction in the number of color channelsrequired to render the light primary colors, it therefore frees a numberof the channels in a carriage or a print head array for other uses.Thus, in one embodiment, the unused channels may be used for anycombination of additional supporting colors or fluids such as cleargloss, clear matte, and an adhesion promoter. Additional colors mayinclude one or more of red, blue, green, orange, white, gray, spotcolors, and other similar colored inks. The inks may be solvent-basedinks, dye sublimation inks, cationic inks, UV curable inks, e-beamcurable inks, or other similar inks.

In an embodiment, either of a print head array or a carriage may includecuring stations attached to sides of the carriage or print head array tocure or dry fluids deposited by the print heads on the substrate duringprinting. The curing stations may include UV lamp systems, cold UV lampsystems, UV-LED lamp systems, infrared heat sources, e-beam lampsystems, hot air convection systems or other similar systems for curingor drying.

As above, compositing light colors from a transparent white ink andprimary color inks reduces the overall number of print channels requiredin a full-color inkjet printer. While the extra channels may be used todeliver additional liquids and ink colors, an embodiment eliminates theunneeded channels completely, allowing a significant reduction in designand manufacturing costs of an inkjet printer, with the result being asimpler print apparatus that is easier and less expensive tomanufacture. Typically, the cost saving is achieved from elimination ofthe additional ink jet print heads, electronics supply systems and otherhardware required to support the customary number of ink channels. Thereduction in manufacturing cost may, of course, be ultimately passed onto end users. Thus, the cost to acquire and own an inkjet printapparatus that has the capability to render light primary colors usingtransparent white ink is significantly reduced.

Additionally, the reduction in the number of ink channels may beachieved without sacrificing smooth color transitions, thus maintainingquality of final, printed image.

Compositing light primary colors from transparent white ink provides anumber of other advantages;

-   -   The end user need inventory a smaller number of inks, for        example, five inks instead of eight;    -   Printing cost per square foot is reduced, thus allowing the end        user to compete more effectively with others in the same line of        business;    -   A broader range of colors is attainable. The use of the        transparent white allows for the use of stronger saturated        primary colors. With the use of stronger saturated primary inks        in combination with the transparent white, the color gamut can        be expanded into currently unattainable saturated areas as well        as very light, clean-hue areas;    -   In an embodiment, a user may “field upgrade” a printer equipped        to print with the four primary colors and transparent white to a        device having eight or more channels some time after initial        purchase, allowing him or her to buy in at lower cost and        upgrade to enhance print capabilities by using some combination        of: orange, green, blue, violet, red, blue, white, metallics,        clear gloss, clear matte, adhesion promoter, and so on.

As above a print system 10 may include one or more carriages 18, eachcarriage including a number of print heads 32. Referring now to FIG. 2,shown is a more detailed representation of the carriage 18 shown inFIG. 1. In an embodiment, for each color channel, the carriage 18 mayhave installed therein, at least one secondary ink reservoir 26. Eachsecondary ink reservoir is in fluid communication with a primary inkreservoir (not shown) by means of at least one solenoid valve 24. Inturn, each secondary ink reservoir is in fluid communication with atleast one print head 32 by means of at least one second solenoid valve28 and at least one liquid line 30. It will be appreciated that thecarriage 18 may provide as few as five color channels or up to ten, oreven more channels. FIG. 3, for example, shows an embodiment wherein thecarriage 18 includes a total of seven channels: two for opaque white 34,and one each for yellow 36, cyan 38, magenta 40, black 42 andtransparent white 44. A fuller description of the carriage may be foundin U.S. Pat. No. 7,396,119, the entirety of which is incorporated hereinby this reference thereto.

Formulation of a Transparent White Ink Composition

A transparent white ink is formulated to brighten, lighten and or dilutefull-tone primary inkjet colors (cyan-magenta-yellow-black). Anembodiment of a transparent white ink composition may be formulatedaccording to methods and formulae described in United States patentapplication pub. no. 2011/0045199, which is hereby incorporated hereinin its entirety. As described in the 199 publication, a radiationcurable ink composition may comprise one or more of:

-   -   a dendritic or hyperbranched polyester acrylate component;    -   an oligomer component;    -   a monomer component;    -   a photo-initiator component;    -   a colorant component; and    -   an additive component.

Dendritic or Hyperbranched Polyester Acrylate Component

In embodiments, the dendritic or hyperbranched polyester acrylatecomponent may comprise 10-45% by weight of the ink compositions. In afurther embodiment, the dendritic or hyperbranched polyester acrylatecomponent may comprises 10-30% by weight of the ink compositions. In astill further embodiment, the dendritic or hyperbranched polyesteracrylate component comprises 10-25% by weight of the ink compositions.

In an embodiment, the dendritic or hyperbranched polyester acrylate inthe component has a functionality of greater than 5. In otherembodiments, the dendritic or hyperbranched polyester acrylate in thecomponent has a functionality in the range of 6-12.

Oligomer Component

The ink compositions comprise an oligomer component. In an embodiment,the amount of the oligomer component in the ink compositions may be1-15% by weight. In an embodiment, the amount of the oligomer componentmay be 5-10% by weight. In an embodiment, the oligomer component maycomprise at least one of:

-   -   an acrylic oligomer;    -   a urethane (meth)acrylate oligomer;    -   a polyester based (meth)acrylate oligomer; and    -   a polyether based (meth)acrylate oligomer and    -   an epoxy (meth)acrylate oligomer.

One of more embodiments use an oligomer component of low viscosity, lowvolatility, high reactivity, low glass transition temperature, and goodadhesion to multiple substrates in the ink compositions. In anembodiment, the functionality of the oligomer component is not greaterthan 3. In an embodiment, the functionality of the oligomer component isnot greater than 2. The low functionality contributes to more flexibleink compositions. An oligomer component combined with a hyperbranchedpolyester acrylate component can significantly improve ink adhesion to awide range of substrates, including substrates that are difficult forradiation curable inkjet inks to adhere to, such as polyolefins.

Monomer Component

The ink composition may also comprise a monomer component. The amount ofthe monomer component in the ink composition may be 30-80% by weight inone embodiment. In one embodiment, the monomer component may be 30-60%by weight of the ink composition. The type and amount of monomercomponent is selected to offer good solvency to the dendritic orhyperbranched polyester acrylate component and the oligomer component inink formulations, which dilutes the ink to a low viscosity. In anembodiment, the monomer component may have low glass transitiontemperature, which contributes to the flexibility of ink after curing.In an embodiment, the functionality of the monomer does not exceed 2 tocreate more flexible ink compositions.

In one embodiment, the monomer component comprises both monofunctionaland difunctional monomers.

Examples of suitable mono-functional monomers include, but are notlimited to, tetrahydrofurfuryl acrylate, tetrahydrofurfurylmethacrylate, vinyl caprolatam, isobornyl acrylate, isobornylmethacrylate, 2-phenoxyethyl acrylate, 2-phenoxyethyl methacrylate,2-(2-ethoxyethoxy)ethyl acrylate, isooctyl acrylate, isodecyl acrylate,isodecyl methacrylate, lauryl acrylate, lauryl methacrylate, stearylacrylate, stearyl methacrylate, cyclic trimethylolpropane formalacrylate, 3,3,5-trimethylcyclohexane acrylate, and monofunctionalmethoxylated PEG (350) acrylate, etc.

Examples of suitable di-functional monomers include, but not are limitedto, diacrylates or dimethacrylates of diols and polyetherdiols, such aspropoxylated neopentyl glycol diacrylate, 1,6-hexanediol diacrylate,1,6-hexanediol dimethacrylate, 1,3-butylene glycol diacrylate,1,3-butylene glycol dimethacrylate 1,4-butanediol diacrylate,1,4-butanediol dimethacrylate, alkoxylated aliphatic diacrylate (e.g.SR9209A from Sartomer®), diethylene glycol diacrylate, diethylene glycoldimethacrylate, dipropylene glycol diacrylate, tripropylene glycoldiacrylate, triethylene glycol dimethacrylate, and alkoxylated hexandioldiacrylates, e.g SR562, SR563, SR564 from Sartomer®.

Photo-Initiator Component

The ink composition may comprise a photo-initiator component. In theradiation curing process, the photo-initiator component initiates thecuring in response to incident radiation. The amount of aphoto-initiator component in the ink compositions may be 1-20% byweight. In an embodiment, the amount of photo-initiator component may be5-15% by weight. The selection of the type of photo-initiator componentin the ink compositions is generally dependent on the wavelength ofcuring radiation and the colorant employed in the ink compositions. Inan embodiment, the peak absorption wavelengths of selectedphoto-initiator vary with the range of wavelength of curing radiation toeffectively utilize radiation energy, especially using ultraviolet lightas radiation.

Examples of suitable photo-initiators include, but are not limited to,1-hydroxycyclohexylphenyl ketone, 4-isopropylphenyl-2-hydroxy-2-methylpropan-1-one,1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one,2,2-dimethyl-2-hydroxy-acetophenone, 2,2-dimethoxy-2-phenylacetophenone,2-hydroxy-2-methylpropionphenone, Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide,bis(2,6-dimethoxy-benzoyl)-2,4,6 trimethyl phenyl phosphine oxide,2-methyl-1-1[4-(methylthio)phenyl]-2-morpholino-propan-1-one,3,6-bis(2-methyl-2-morpholino-propionyl)-9-n-octylcarbazole,2-benzyl-2-(dimethylamino)-1-(4-morpholinyl)phenyl)-1-butanone,benzophenone, 2,4,6-trimethylbenzophenone, isopropyl thioxanthone.Suitable blends of photo-initiators commercially available include, butare not limited to, those under the designations of Darocur 4265,Irgacure 2022, Irgacure 2100 from Ciba® Specialty Chemicals; and EsacureKT37, Esacure KT55, Esacure KTO046 from Lamberti®.

The photo-initiator component may further comprise a co-initiator. Theamount of co-initiator component may be 0-15% by weight of the inkcompositions, or, in at least one embodiment, 0-10% by weight of the inkcompositions, or, in at least one embodiment, preferably 2-7% by weightof ink compositions. The co-initiator component is used to activatephoto-initiators to initiate polymerization or is used to improve thesurface curing of ink by mitigating oxygen inhibition to free radicalsgenerated by photo-initiators. Examples of suitable co-initiatorsinclude, but are not limited to, those under the designations of CN386,CN384, and CN383 from Sartomer® and Ebecryl 7100 from Cytec® SurfaceSpecialty.

Additive Component

In an embodiment, the ink compositions further comprise an additivecomponent. Various additives can be included in the ink compositions,including a surfactant, a leveling additive, or a stabilizer, and so on.

A surfactant may be used to reduce the surface tension of the inkcompositions to improve wetting property of the inks on substrates. Theamount of surfactant in the ink compositions is 0.01-2% by weight, andpreferably 0.05-0.5% by weight. It is preferred that the surfactantcomprises at least one polysiloxane acrylate, also known as a siliconeacrylate, which participates in the radiation curing process to be partof cured ink. Examples of a suitable surfactant include, but are notlimited to, those under the designations of Tegorad 2200N, Tegorad 2100,and Tegorad 2300 from Goldschmidt® Chemical Corp., and BYK 377, BYK3510, BYK 307, and BYK 330 from BYK Chemie®.

A leveling additive may be used to improve the flowing property of inkto produce a more uniform surface of ink film. The amount of levelingagent in the in compositions is 0.1-2% by weight. Examples of suitableleveling agents include, but are not limited to, those under thedesignation of BYK 361N, BYK 353, and BYK 354 etc. from BYK Chemie®.

A stabilizer may be used to improve shelf life and photolytic stabilityof ink compositions. Stabilizers in the ink compositions can include anultraviolet light stabilizer, a free radical scavenger stabilizer, etc.Examples of ultraviolet light stabilizers include ultraviolet absorberstabilizer and hindered amine light stabilizer. These stabilizers areused to improve the outdoor durability and weatherability of cured ink.Commercially available ultraviolet light stabilizers include, but arenot limited to, those under the designation of Tinuvin 460, Tinuvin 479,Tinuvin171, Tinuvin 928, Tinuvin123, and Tinuvin 292 from Ciba®Specialty Chemicals, etc. They can be present in the ink compositions inamounts of 0.01%-2% by weight, and more specifically 0.1%-1% by weight.

A free radical scavenger stabilizer may be used to improve the stabilityof ink against heat. Examples of a free radical scavenger include, butare not limited to, hydroquinone, 4-methoxyphenol, hindered phenol, etc.The amount of free radial scavenger stabilizer can be present in inkcompositions in 0.05-1% by weight, and more specifically 0.1-0.75% byweight. A small amount is preferably used in the ink compositions tominimize their interference with the radiation curing process.

Colorant Component

An exemplary opaque white ink formulation may contain a colorantcomponent comprising a titanium dioxide based pigment in an amount at 5%by weight. An embodiment of the transparent white ink formulation maycontain colorant at the amount 2.5% by weight, or less. In anembodiment, the colorant component may constitute 1.5% or less byweight.

One skilled in the art will readily understand that the transparentcharacter of the transparent white ink formulation is achieved throughdegrees of dilution of the colorant.

In an embodiment, zinc oxide-based pigment is used instead of titaniumdioxide. The zinc-oxide pigment offers the advantage of being inherentlymore transparent than the titanium-based pigment. The opticalcharacteristics of the zinc oxide-based pigment allow formulation of thetransparent white ink composition with greater amounts of colorant thanwith titanium dioxide-based pigment, thereby providing a salutary effecton the stability of the transparent white ink composition. Duringstorage and during use, it is desirable to circulate the ink regularlyin order to keep the colorant component in suspension.

Application of a Transparent White Ink Composition

In an embodiment, the transparent white inkjet ink is jetted in the samepass 50 of the carriage 18 as the primary colors are jetted, as shown inFIG. 4. When being jetted with the transparent white ink 54, the amountof full-tone primary ink 52 is reduced. The transparent white ink 54 isonly jetted onto the substrate 46 concurrently with the full-toneprimary ink 52 in lighter tonal areas conventionally supported by lightprimary inkjet inks: light cyan; light magenta; light yellow and lightblack.

In an embodiment the primary color 52 and the transparent white 54 arejetted onto the same area conventionally supported by light primaryinkjet inks in succession, but with no curing in between the applicationof the two inks. As shown in FIG. 4, an embodiment of the carriage 18may include one or more cure lamps 48. In an embodiment, the primarycolor 52 is applied first. In a further embodiment, the transparentwhite 54 is applied first.

The end result of jetting of the primary 52 and transparent white 54inks without curing between application of each is the mixing of the twoinks on the substrate 46 to produce a composite light primary color ink.

Following application of the two inks, the composite ink is cured ordried by means of a cure lamp 48.

In an embodiment, the foregoing principles may be applied to theproduction of any sort of composite ink by jetting at least two inksonto the same region of the substrate without curing in betweenapplication of each ink. Application of the inks may either byconcurrent or it the inks may be applied in rapid succession. The resultof apply multiple inks to the same region of the substrate withoutcuring in between application of each ink is that the inks combine onthe substrate, blending to form a single, composite ink. Followingapplication of the separate inks, the resulting composite ink may becured as described herein above. Additionally, at least one of thesubstances may be a liquid other than an ink, such as a solvent, asurfactant or a drier.

Printer Controller

It is to be appreciated that the operations involved in compositing oftransparent white ink and primary color inks to produce composite lightprimary color inks immediately upon the substrate are performed underthe direction of a control means such as a raster image processor (RIP).

As shown in FIG. 5, the system may include a printing device 10 and acontroller 52. In an embodiment, the controller 56 may be a raster imageprocessor (RIP) such as the FIERY raster image processor produced byELECTRONICS FOR IMAGING, Inc. (Foster City, Calif.). In an embodiment,the RIP may be implemented as a firmware program executed on aprocessing element, such as a microprocessor, integrated with the inkjetprinting device 10. In an embodiment, the RIP may be a stand-alonehardware RIP. In a still further embodiment, the RIP may be a softwareprogram operating on a server or a workstation, for example, a colormanagement server, within a network of computing devices as describedherein below in connection with FIG. 6.

Referring now to FIG. 6, shown is a diagrammatic representation of amachine in the exemplary form of a computer system 600 within which aset of instructions for causing the machine to perform any one of themethodologies discussed herein may be executed. In alternativeembodiments, the machine may comprise a network router, a networkswitch, a network bridge, personal digital assistant (PDA), a cellulartelephone, a web appliance or any machine capable of executing asequence of instructions that specify actions to be taken by thatmachine.

The computer system 600 includes a processor 602, a main memory 604 anda static memory 606, which communicate with each other via a bus 608.The computer system 600 may further include a display unit 610, forexample, a liquid crystal display (LCD) or a cathode ray tube (CRT). Thecomputer system 600 also includes an alphanumeric input device 612, forexample, a keyboard; a cursor control device 614, for example, a mouse;a disk drive unit 616, a signal generation device 618, for example, aspeaker, and a network interface device 628.

The disk drive unit 616 includes a non-transitory machine-readablemedium 624 on which is stored a set of executable instructions, i.e.software, 626 embodying any one, or all, of the methodologies describedherein. The software 626 is also shown to reside, completely or at leastpartially, within the main memory 604 and/or within the processor 602.The software 626 may further be transmitted or received over a network630 by means of a network interface device 628.

In contrast to the system 600 discussed above, a different embodimentuses logic circuitry instead of computer-executed instructions toimplement processing the various methodologies herein described.Depending upon the particular requirements of the application in theareas of speed, expense, tooling costs, and the like, this logic may beimplemented by constructing an application-specific integrated circuit(ASIC) having thousands of tiny integrated transistors. Such an ASIC maybe implemented with CMOS (complimentary metal oxide semiconductor), TTL(transistor-transistor logic), VLSI (very large scale integration), oranother suitable construction. Other alternatives include a digitalsignal processing chip (DSP), discrete circuitry (such as resistors,capacitors, diodes, inductors, and transistors), field programmable gatearray (FPGA), programmable logic array (PLA), programmable logic device(PLD), and the like.

It is to be understood that embodiments of this invention may be used asor to support software programs executed upon some form of processingcore (such as the Central Processing Unit of a computer) or otherwiseimplemented or realized upon or within a machine or computer readablemedium. A machine-readable medium includes any mechanism for storing ortransmitting information in a form readable by a machine, e.g. acomputer. For example, a machine readable medium includes read-onlymemory (ROM); random access memory (RAM); magnetic disk storage media;optical storage media; flash memory devices; electrical, optical,acoustical or other form of propagated signals, for example, carrierwaves, infrared signals, digital signals, etc.; or any other type ofmedia suitable for storing or transmitting information.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will, however,be evident that various modifications and changes may be made theretowithout departing from the broader spirit and scope of the invention asset forth in the appended claims. The specification and drawings are,accordingly, to be regarded in an illustrative sense rather than arestrictive sense.

1. A transparent white inkjet ink comprising one or more of: a dendriticor hyperbranched polyester acrylate component present in saidcomposition in an amount of 10% to 45% by weight of said composition; anoligomer component present in said composition in an amount of 1% to 15%by weight of said composition; a monomer component present in saidcomposition in an amount of 30% to 60% by weight of said composition; aphoto-initiator component present in said composition in an amount of 1%to 20% by weight of said composition; and a colorant component presentin said composition in an amount of no greater than 5% by weight of saidcomposition, said colorant comprising at least one white pigment.
 2. Theink composition of claim 1, wherein said at least one pigment comprisesat least one compound selected from a group including: titanium dioxideand zinc oxide.
 3. The ink composition of claim 1, further comprising anadditive component, said additive component including at least oneselected from a group comprising: at least one surfactant present insaid composition in an amount of 0.01% to 2% by weight of saidcomposition; at least one leveling additive present in said compositionin an amount of 0.01% to 2% by weight of said composition; and at leastone stabilizer present in said composition in an amount of 0.01% to 2%by weight of said composition.
 4. The ink composition of claim 1,further comprising a co-initiator component present in said compositionin an amount no greater than 15% by weight of said composition.
 5. Amethod for producing a composite lightened primary color inkjet inkcomprising: jetting an amount of a first inkjet ink onto a predeterminedregion of a substrate; while said first inkjet ink remains uncured,jetting an amount of a second inkjet ink onto said predetermined regionof said substrate; wherein said first ink is selected from a groupcomprising a primary color inkjet ink and a transparent white inkjet inkas in claim 1 and wherein said second inkjet ink comprises the remaininginkjet ink in said group after selection of said first inkjet ink; andcuring said amounts of said first and second inkjet inks jetted ontosaid predetermined region; wherein blending of said first and secondinkjet inks on said predetermined region in their uncured state producesa composite lightened primary color inkjet ink.
 6. The method of claim5, wherein said first inkjet ink comprises said primary color inkjet inkand wherein said second inkjet ink comprises said transparent whiteinkjet ink
 7. The method of claim 5, wherein said first inkjet inkcomprises said transparent white inkjet ink and said second inkjet inkcomprises said primary color inkjet ink.
 8. The method of claim 5,wherein said primary color inkjet ink is selected from a groupconsisting of cyan, magenta, yellow and black inkjet inks.
 9. The methodof claim 5, wherein said amount of said transparent white inkjet ink isselected to lighten said primary color inkjet ink by a predeterminedamount.
 10. The method of claim 5, wherein said lightened primary colorinkjet ink comprises a replacement for a pre-formulated light primarycolor inkjet ink.
 11. The method of claim 10, wherein said predeterminedregion comprises a region specified by a page description to receive alight primary color inkjet ink.
 12. The method of claim 5, furthercomprising: jetting said first and second inkjet inks from separatecolor channels.
 13. A method for producing a lightened primary colorinkjet ink comprising: blending a primary color inkjet ink and atransparent white inkjet ink by jetting both inks onto a predeterminedarea of a substrate so that the two inks blend with each other in thepredetermined area of the substrate, wherein sad blended inks comprise alightened primary color inkjet ink; and curing said blended inks.
 14. Asystem for producing a composite lightened primary color inkjet inkcomprising: a plurality of inkjet inks, each of a different primarycolor; a transparent white ink as in any of claims 1-4; an inkjetprinter having a plurality of color channels; a controller for saidinkjet printer; and program code for controlling said inkjet printer,which when executed by said controller causes said inkjet printer toperform computer-implemented operations including: allocating one ofsaid plurality of color channels for delivery of said transparent whiteink to a substrate; responsive to instructions from a page descriptionto deliver a pre-formulated light inkjet ink of a predetermined primarycolor to a predetermined region of said substrate: jetting an amount ofa first inkjet ink onto said predetermined region; while said firstinkjet ink remains uncured, jetting an amount of a second inkjet inkonto said predetermined region of said substrate; wherein said first inkis selected from a group comprising the primary color inkjet inkspecified by said page description and the transparent white inkjet inkand wherein said second inkjet ink comprises the remaining inkjet ink insaid group after selection of said first inkjet ink; and curing saidamounts of said first and second inkjet inks jetted onto saidpredetermined region; wherein blending of said first and second inkjetinks on said predetermined region in their uncured state produces alightened primary color inkjet ink that replaces said pre-formulatedlight inkjet ink specified by said page description.
 15. The system ofclaim 14, wherein said first inkjet ink comprises said primary colorinkjet ink and wherein said second inkjet ink comprises said transparentwhite inkjet ink.
 16. The system of claim 14, wherein said first inkjetink comprises said transparent white inkjet ink and said second inkjetink comprises said primary color inkjet ink.
 17. The system of claim 14,wherein said primary color inkjet ink is selected from a groupconsisting of cyan, magenta, yellow and black inkjet inks.
 18. Thesystem of claim 14, wherein said amount of said transparent white inkjetink is selected to lighten said amount of primary color inkjet ink to alightness equal to that of said pre-formulated light inkjet inkspecified by said page description.
 19. The system of claim 14, thecomputer-implemented operations further comprising: jetting said firstand second inkjet inks from separate color channels.
 20. A method forproducing a composite inkjet ink comprising: jetting at least one liquidinkjet ink onto a predetermined region of a substrate; while said atleast one liquid inkjet ink remains uncured, jetting an amount of atleast one second liquid onto said predetermined region of saidsubstrate; wherein said at least one second liquid is selected from agroup comprising at least one further inkjet ink different from said atleast one liquid inkjet ink and at least one non-ink liquid; whereinsaid at least one liquid inkjet ink jetted onto said predeterminedregion of said substrate and said at least one second liquid jetted ontosaid predetermined region of said substrate blend to form a singlecomposite inkjet ink.